Boston was battered but vigilant on Tuesday as an army of federal agents raced to find out who attacked the cityâs historic marathon, leaving three dead and more than 100 injured amid a war zone of shattered glass and bomb debris on Patriots Day.

As of Tuesday morning, no persons or group had claimed credit for twin explosions at the finish line near Bostonâs Copley Square. The Pakistani Taliban, a group that has threatened the United States in the past, denied participation, according to the Associated Press.

Law enforcement officials questioned an injured Saudi national at a local hospital, but news stories indicated that the individual appears to have no connection to the case. The Boston Globe reported that he was simply a frightened spectator who had tried to flee but was tackled and restrained by bystanders.

On Monday night agents from the FBI, the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF), and other law enforcement agencies raided a unit in a high-rise apartment on Ocean Drive in the seaside Boston suburb of Revere, according to information posted online by a participating local fire department. Several bags, including what appeared to be a large

duffel bag, were removed from the scene. Authorities were mum as to the specifics of their suspicions but confirmed that the Revere search was related to the case.

Rep. William Keating (D) of Massachusetts, a member of the House Homeland Security Committee, told a local CBS reporter that the two bombs at the finish line, which exploded seconds apart, had been stashed in trash receptacles and were clearly a âcoordinated attack.â Authorities have discovered two other unexploded devices, he told Bostonâs WBZ News.

Other reports said no unexploded devices had been found. A reported fire at Bostonâs John F. Kennedy Presidential Library turned out to be the result of an electrical problem and was unrelated to the marathon bombs, according to Boston police.